DUBLIN, Ireland: Almost two out of five voters remain undecided ahead of Ireland's presidential election on October 24, according to the latest Ireland Thinks/Sunday Independent opinion poll.

The survey places Fine Gael's candidate, former minister Heather Humphreys, in a narrow lead with 21 percent support. She is followed closely by Jim Gavin, the former Dublin football manager, and Independent TD Catherine Connolly, who each registered 20 percent. Musician and activist Bob Geldof also featured among the leading contenders.

Despite the early standings, a striking 39 percent of respondents said they did not yet know who they would vote for. Analysts say the unusually high number of undecided voters could play a decisive role in shaping the race.

Fine Gael formally selected Humphreys as its candidate, while Fianna Fáil and Sinn Féin are expected to confirm their choices in the coming week. Within Fianna Fáil, MEP Billy Kelleher and Gavin will compete for the nomination in a secret ballot of the parliamentary party on September 9.

The poll also asked voters about potential endorsements. More than a third said Fianna Fáil should back its own candidate, while about one in five said Sinn Féin should support Connolly.

Political debate has already emerged over the question of endorsements. On Newstalk, DCU politics professor Gary Murphy said he believed Fianna Fáil was right not to support former Taoiseach Bertie Ahern.

For Sinn Féin, party leader Mary Lou McDonald ruled herself out of the race. Speaking on RTÉ's Morning Ireland on September 8, she said her priority was to focus on a general election and the goal of changing government, rather than seeking the presidency.

McDonald added that she faced no pressure from within her party to run and stressed the importance of holding the current Fianna Fáil–Fine Gael coalition to account. "I have to lead from the front," she said, noting that Sinn Féin had tested "every proposition" before deciding on its candidate.

She declined to name a possible nominee but did not rule out Northern Ireland's First Minister Michelle O'Neill.